Benzathine Penicillin

Indications

Benzathine Penicillin is used for: Acute otitis media, Group A Strep. infections, Rheumatic fever, Syphilis, Neurosyphilis, Streptococcal impetigo, Anthrax, Diphtheria, Uncomplicated pneumococcal pneumonia, Streptococcal pharyngitis

Adult Dose

Adult: IM: 0.3 to 1.2 million units up to 2.4 million units as a single dose repeated every five to seven days. Specific dosage schedule: Treatment of group-A beta-haemolytic streptococcal infections: A single intramuscular dose of 600,000 units. Prevention of rheumatic fever: Monthly injection of a single dose of 1.2 million units is the most effective regimen for preventing further attacks of rheumatic fever. Treatment of acute otitis media: A single injection of 600,000 units. Treatment of syphilis: Early syphilis- 2.4 million units as a single dose. Late syphilis- 2.4 million units weekly for three successive weeks. Neurosyphilis- Benzylpenicillin, intravenously, 2 to 4 million units every 4 hours for 10 days, followed by benzathine penicillin intramuscularly, 2.4 million units weekly for three successive weeks. Congenital syphilis: Asymptomatic infants with normal cerebrospinal fluid, intramuscularly 50,000 units per kg in a single dose. Primary and secondary syphilis have been treated with single injections of 2.4 million units of long acting benzathine penicillin weekly for 2 to 4 weeks with satisfactory results.

Child Dose

Child: IM 50,000 U/kg for newborns and infants, Child: IM 50,000 U/kg for newborns and infants, children <60 lb: 300,000–600,000 U, children >60 lb: 900,000 U 1 dose for treatment

Renal Dose

Administration

Contra Indications

Hypersensitivity to penicillins or cephalosporins. IM inj (ischaemic reactions may occur).

Precautions

Very high doses in poor renal function (risk of neurotoxicity) or heart failure. Avoid contact, skin sensitization may occur. Monitor serum potassium concentration, renal and haematological status. Spirochete infections particularly syphilis; suprainfection with penicillin-resistant organisms with prolonged use; avoid intrathecal route. Lactation: Excreted into breast milk, caution advised

Pregnancy-Lactation

Pregnancy Category: B Lactation: Excreted into breast milk, caution advised

Interactions

Probenecid prolongs T1/2 of benzathine benzylpenicillin. Bacteriostatic drugs e.g. chloramphenicol, tetracyclines; other antibacterials; anticoagulants.

Adverse Effects

Side effects of Benzathine Penicillin : Hypersensitivity reactions including uticaria; fever; joint pains; rashes; angioedema; serum sickness-like reactions; haemolytic anaemia; interstitial nephritis; neutropenia; thrombocytopenia; CNS toxicity including convulsions; diarrhoea; antibiotic-associated colitis. Potentially Fatal: Anaphylaxis

Mechanism of Action

Benzathine benzylpenicillin has the same antimicrobial action as benzylpenicillin which exerts its bactericidal action on growing and dividing bacteria by inhibiting bacterial cell wall synthesis. IM admin results in a prolonged effect, but because of its relatively low blood concentrations, its use should be restricted to microorganisms that are highly susceptible to it.